Moped Army

I've been reading through the archived stuff and I'm still stuck. If I missed an already existing thread, please link me to it if you know it off hand.

I finally got my 78 SSXL running smoothly, but my stock exhaust is no good. It's super loud, so I'm assuming the baffles are out or something...which I'm guessing is putting strain on the motor. I'm new to all this. What's a decent upgrade/performance pipe that I can bolt right on (if any)? If I absolutely need to weld and modify something, what should I buy and how do I do it? I haven't modified the engine/motor at all yet, but I might buy a performance kit in the future. I assume this would affect what kind of pipe I buy. Thanks folks.

P.S. I understand how a 2-stroke motor works and I'm mechanically inclined, but I don't know _anything_ about performance stuff.